Film for photographic purposes



Patented Apr. 18,l 1933 visura-D STAT-Es PATENT I OFFICE LIMITED, OF LONDON', ENGLAND, .AND HIMISELF FILI FOR PHOTOGRAPHE? PURPOSES Application :Bled September 11, 1931, Serial No. 562,411, and in Great' Britain September 13, 1980.-

The object of the present invention is to provide an' improved photographic film of non-inflammable character adaptedrparticularly for use in kinematographlc apparatus.

A non-inflammable photographic film for use in kinematographic apparatus has long been sought, but so far, all such films as have satisfied requirements regarding non-inflammability have been defective in some other respect, the most general defects being brittleness or lack of permanent iiexibility and a tendency to react with the chemical constituentslofi the photographic image, which is thus spoi e A film embodying this invention, which is non-inflammable, exible, transparent, substantially colorless and free of any danger of affecting the photographic image, is illustrated by the attached drawing, showing the same in longitudinal section on a greatly enlarged scale. Said lm according to the invention consists in a thin core layer 1 of insoluble gelatine, coated on each s1de with a thin layer or coating 2 of rubber, which inits turn is covered with an outer layer or coating 3 of celluloid, collodion or other varnish.i

The purpose of the layers of rubber and varnish is to provide a complete inseparable q coating protecting the central o r core film from any action by water or the various salts used in the development and fixing of the photographi image, and adapted tonreceive on one side the sensitized emulsion without risk of the hotographic image bein detrimentally aiiiected. The completed lm, although it has a coating of a highly infiammable character such as celluloid, remains non-iniiammable, that is to say, when a ame is applied to the film or it is hghl heated, all that happens is that the film cur s up and hardens but does not ignite. Y

In carrying out the invention the following procedure may be adopted.

A warm solution of gelatine -i-n water, to which a very small proportion of formaldehyde has vbeen added. (forlinstance about 1% of a 40% solution of formaldehyde) is flowed or poured on to a level travelling metal band, on which it is carried in the'form `to -iind its own level, the band then ca of a film through a cooling chamber, where the gelatine sets and becomes insoluble and is then carried on into a current of warm air whereby it is dried. In some cases, to hasten the drying, the gelatine film may be drawn -tlhough alcohol before being subjected to .ummm Groen manson, orA LoNnoN, ENGLAND, assrenoa To w.n.'s'r1r.r. a'soNs In order to ensure regularityin the thickl ness of theI core layer and to prevent floodin the gelatine is extruded or delivered throng a suitable die onto the 'metal band at av temperature only a few. degrees above its v setting point and under such pressure 'as the speed of the moving metal band may re uire. The metal band, before it reaches the' ie, is cooled considerably below the setting point of the gelatine, so that the surface of the gelatine in contact with the cooll metal will set uickly and prevent flooding, while the main bulk of the gelatine will remainliuid enough 111g itronthrough the cooling chamber to finally set-the whole.

The gelatine supportin metal band is next high treated with a solution of wax in benzole or the like, so that after the gelatinefilm has been finally dried, it can be easily stripped olf. The film of gelatinel is then thinly surface ofthe coated on both sides with rubber varnish, which may consist of a small percentage pressure rollers to ensure a brig t surface y polished anddried, the .film may be passed' between ig l polished 100 and improve the adhesion of the separate layers.

It is preferred to use as the outer protecting medium a solution of celluloid such as now used in making films, because althouoh highly inflammable in itself, it imparts to t e I film, surfaces having the same other characteristics as an ordinary Celluloid film. Collodion varnish may be used instead of celluloid varnish, as the outer coating.

Instead of adding the formaldehyde or other agent to the gelatine solution, the set gelatine film may bedraWn through or immersed in an aqueous or alcoholic solution of formaldehyde or other agent which also will renderit insoluble without reducing its transparency or flexibility.

A coat of sensitized gelatine .emulsion can be applied to a film according to this invention in the ordinary Way and the film can then be dealt -vvith in the same vvay as a celluloid film Without risk of the ultimate photo graphic image being affected, or of the coatings of rubber and celluloid separating from each other or from thegelatine core, while p the transparency, fiexibility, colourlessness and durability of the film are adequate for all ordinary purposes.

`What I claim is Y 1. A non-inflammable photographic film, which consists of a .core layer of gelatine, rendered insoluble and coated on each side first with rubber a-nd'then with another protecting medium such as celluloid.

2. A non-inflammable photographic film comprising a core layer of gelatine, rendered insoluble by asubstance, and having a coating of rubber varnish on each-side with an outer coating-of another protective medium such as celluloid thereon.

3L .A non-inflammable film for photographic purposes, which consists of a core consists in first forming a core layer of gelatine from a warm aqueous solution contain- 'mable film for photographic purposes, which consists in first forming a core layer of gelatfne from a warm aqueous solution contain- `inga small proportion of form'aldehydeand a trace of glycerine, coolin and drying the gelatine core layer, coating oth sides thereof with a rubber varnish, and then coating the same with a Celluloidvarnish.

Signed at London, England, this 19th day of August, 1931. .l

ANDREW GEORGE ADAMSON.

' layer of gelatine, rendered insoluble by a substance; the same being coatedA on each side with a thin sub-surface of rubber varnish and with a thin outer surface of another protecting medium such as celluloid. l 4. A non-infiammable photographic filmh which consists of a core layer of gelatine, rendered insoluble by formaldehyde and i coated on each side first with rubber and then with another protecting medium such as celluloid. Y

5. The process of making a non-infiammable film for photographick purposes, which consists in first` forming a core layer of gelatine from 'a .warm aqueous solution containing al small proportion of an agent vadapted to render the gelatine insoluble, cooling and drying the gelatine core layer, applyto each side of said layer a' coating of thereto a coating of a Celluloid solution.

V6. The process of making a non-inflam 5 mablelm -for photographic purposes, which r rubber solution and thereafter applying 

